KR100507185B1 - a method for detection of thermostat fail in a car - Google Patents

Abstract

The present invention provides a cooling device for a vehicle, for the purpose of accurately determining failure determination of a thermostat by cooling water temperature correction for running wind;

When the engine is started, accumulating the traveling vehicle speed and determining whether the thermostat failure diagnosis execution condition is satisfied; Setting a determination initial setting time according to the intake air amount when the thermostat failure diagnosis execution condition is satisfied in the above step, and subtracting the initial setting time to 0 time; Determining a change in the intake air amount during the initial setting time reduction in the determination step, resetting the thermostat failure determination time when the intake air amount changes, and subtracting it to zero time; Storing the cooling water temperature and calculating an average of the accumulated vehicle speed when the thermostat failure determination time subtracted in the step reaches 0 time point; Calculating a coolant temperature basic determination temperature correction value according to the driving wind effect according to the average value of the vehicle speed calculated in the step; Compensation value of the basic determination temperature correction temperature according to the influence of the running wind calculated in the above step is to determine whether the thermostat failure compared to the actual cooling water temperature, thereby improving the failure diagnosis performance, thereby reducing the fault determination by , Reducing the cost of troubleshooting and reducing costs,

The temperature range can be expanded at the start of the current fault determination conditions, enabling the monitoring of the entire operation area.

Description

Thermostat fault diagnosis method {a method for detection of thermostat fail in a car}

The present invention relates to a method for diagnosing a thermostat failure of a vehicle engine, and more particularly, a failure diagnosis of a thermostat that regulates the flow of an engine coolant for preventing overheating of an engine of a vehicle is performed by high winds. To troubleshoot the thermostat to prevent failure.

In general, the cooling device of the vehicle is a device for preventing overheating of the engine of the vehicle, among which the thermostat is installed between the engine and the radiator. It quickly raises the temperature and automatically opens and closes when the temperature is over a certain temperature, thereby maintaining the proper temperature of the coolant cooled by the writer. That is, the thermostat exhibits the best engine performance because the temperature of the engine is constant, and prevents overheating and overcooling of the engine, and also prevents aging of oil and prolongs engine life. It also increases the heating effect in the car, reduces fuel consumption and prevents the consumption of cooling water.

Above, in order to detect when the thermostat is broken in the open state, the cooling water temperature does not reach 77 ° C. after startup and occurs during a certain time even when the cooling water temperature reaches 77 ° C. If not, a thermostat fault is determined. This is a function of the temperature at the start of the engine and the average amount of air (continuously accumulating the amount of air at startup), divided into five zones (1 to 5) according to the average air volume, and the first and fifth temperatures at which the average air volume range changes. It determines the failure by adopting a large value compared with the map determined in.

However, the thermostat failure determination as described above has a high possibility of misdiagnosing as the factors for lowering the temperature rise due to the driving wind during driving of the vehicle cannot be applied on the control. In other words, the running wind is a factor that adversely affects the increase in the coolant temperature as the speed increases, and the influence of the outside air is considerably increased as the outside air temperature is low. Nevertheless, it is only to judge when the correction for this wind is more than normal (usually 10 to 15 Km or more), which implies a problem that the correction of the wind can not be accurately corrected.

This may adversely affect customer dissatisfaction and maintenance costs by turning on the warning lamp due to the possibility of incorrect diagnosis of a thermostat failure.

Accordingly, an object of the present invention is to solve the above problems, in the vehicle cooling apparatus, to provide a thermostat failure diagnosis method that can accurately perform the failure determination of the thermostat by correction for the driving wind will be.

The present invention for achieving the above object,

Determining whether the thermostat failure diagnosis execution condition is satisfied when the engine is started;

Setting a determination initial setting time according to the intake air amount when the thermostat failure diagnosis execution condition is satisfied in the above step, and subtracting the initial setting time to 0 time;

Determining a change in the intake air amount during the initial setting time reduction in the determination step, resetting the thermostat failure determination time when the intake air amount changes, and subtracting it to zero time;

Storing the cooling water temperature and calculating an average of the accumulated vehicle speed when the thermostat failure determination time subtracted in the step reaches 0 time point;

Calculating a coolant temperature basic determination temperature correction value according to the influence during driving according to the average value of the vehicle speed calculated in the step;

Comprising a step of determining whether the thermostat failure by comparing the coolant temperature basic determination temperature correction value calculated in the above step with the actual coolant temperature.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a thermostat failure diagnosis apparatus according to the present invention, Figure 2 a, b is a flow chart of the thermostat failure diagnostic method according to the present invention, Figure 3 is the average vehicle speed compared to the intake air amount according to the present invention Correction constant setting memory map.

1 is a block diagram of a thermostat failure diagnosis apparatus according to the present invention, which detects an engine speed, an intake air amount, a cooling water temperature, a vehicle speed, and the like which vary according to a change in an operation state of a vehicle, and outputs a predetermined electric signal. State detection apparatus 100; The engine operating state detection device 100 receives the engine speed, intake air amount, cooling water temperature, vehicle speed, etc. detected and corrects the change in the running wind when diagnosing the thermostat. An engine control device 200 which outputs a lamp lighting control signal; It consists of a warning device 300 for lighting the warning lamp for requesting the driver to check the engine according to the thermostat failure in synchronization with the warning lamp lighting control signal output from the engine control device 200.

The vehicle operating state detecting apparatus 100 includes an engine speed detecting unit 110 for detecting a change in engine speed that varies according to a change in an operating state of a vehicle;

An intake air amount detector 120 which detects a change in the amount of air sucked into the engine according to a change in the operation state of the vehicle;

An engine coolant temperature detector 130 which detects a change in engine coolant temperature that varies according to a change in an operating state of the vehicle;

The vehicle speed detection unit 140 detects a traveling vehicle speed of the vehicle that is changed according to a change in the driving state of the vehicle.

The thermostat failure diagnosis method having the above-described configuration will be described with reference to FIGS. 2A and 2B.

After the engine is started, the vehicle operating state detecting apparatus 100 detects and outputs an engine speed, an intake air amount, a cooling water temperature, a vehicle speed, and the like, which vary according to a change in the operating state of the vehicle.

Thus, the control device 200 receives the engine speed, intake air amount, cooling water temperature and vehicle speed detected and applied from the vehicle operation state detection device 100 to accumulate the running speed of the vehicle when the vehicle is running (S100, S110).

Subsequently, it is determined whether the control apparatus 200 satisfies a diagnosis condition for diagnosing a failure of the thermostat controlling the flow of the cooling water for preventing overheating of the vehicle engine (S120).

In the above thermostat failure diagnosis condition, the engine coolant temperature is higher than the first set temperature (e.g. 7 ° C), within the second set temperature (e.g. 77 ° C), and the absolute value of the coolant temperature and intake temperature at start-up The difference value must be less than or equal to the third set temperature (eg, 5 ° C.), the fourth set condition (eg, less than 100 sec below 5 g / sec) and the fifth set condition (include 5 g / sec or less) Example: It should be within 48sec / sec and less than 200sec).

If it is determined that the failure diagnosis condition of the thermostat is satisfied, the control device 200 sets an initial time of a diagnosis time according to the intake air amount (S130).

That is, if the amount of air sucked into the engine is the fourth condition that is the minimum amount of intake air (eg, less than 100 sec at 5 g / sec or less), the control apparatus 200 sets the initial temperature of the thermostat diagnosis according to the intake air amount as the sixth set time (eg, : 2000 sec, T) (S131).

However, within the fourth condition (eg, less than 100 sec below 5 g / sec), which is the minimum amount of intake air, and the amount of air drawn into the engine is within the fifth set condition (eg, less than 200 sec above 48 g / sec), which is the highest intake air volume. In operation S132, the control apparatus 200 sets the thermostat diagnosis initial time according to the intake air amount to a seventh set time (eg, 1800 sec, T).

Further, when the amount of air sucked into the engine is greater than or equal to the fifth set condition (eg, 48 g / sec or more and less than 200 sec), the controller 200 sets the thermostat diagnosis initial time according to the intake air amount to the eighth. Set to a time (eg 1600sec, T) (S133).

Thereafter, the control apparatus 200 decreases the thermostat diagnosis initial time T according to the intake air amount set above by 1 sec for every ninth set time (for example, 500 ms), and the amount of intake air sucked into the engine is variable. It is determined whether or not (S140, S150).

T = T-1sec

When the average air amount of the intake air amount sucked into the engine is determined to be changed in comparison with the intake air amount at the time of setting the thermostat diagnosis initial time, the control apparatus 200 determines an area of the average air amount in which the change has occurred. Then, the thermostat diagnosis subtraction time in this changed area is reset (T1) (S160).

That is, assuming that the area before the area is changed by the intake average air amount is the minimum intake air amount area, when it is determined that the intake average air amount to be sucked into the engine is an intermediate area, the control device 200 determines that the intake air amount is variable. After comparing the reduced residence time (T) for the thermostat diagnosis with the reset time (T1) on the set time setting map (not shown) at the temperature at which the area is changed, and taking a large value, Reduce the time (S170, S180).

For example, if the time T1 that is reset in the predetermined time setting map at the temperature at which the area is changed is greater than the reduced residence time T for thermostat diagnosis at the time when the intake air amount is varied, the control device 200 determines the area. Each time of the ninth set time (for example, 500 ms) is decremented by 1 sec until the time T1, which is reset in the predetermined time set map (not shown) at the changed temperature, becomes zero.

T1 = T1-1sec

However, if the reduced residence time T for the thermostat diagnosis at the point of time when the intake air amount is varied in S170 is greater than the time T1 reset in the predetermined time setting map at the temperature at which the area is changed, The device 200 continues to decrement by 1 sec every ninth set time (e.g. 500 ms) until the reduced residence time T for thermostat diagnosis at a time point at which the intake air amount is varied becomes zero.

Thereafter, the control apparatus 200 determines whether the reduction time T or T1 for the thermostat diagnosis is zero, and when it is determined that the time T or T1 becomes zero, the control device 200 determines that the time is zero. The engine coolant temperature (Tem) is stored in a memory, and after calculating an average value of vehicle speeds of the traveling vehicle accumulated in the above-mentioned S110, the cooling water temperature determination temperature due to the running wind effect is corrected (S190 to S220). ).

In the above description, the correction of the cooling water temperature determination temperature due to the running wind influence can be calculated by calculating the determination temperature correction constant for the basic determination temperature x running wind influence stored in the memory.

The basic judgment temperature stored in the memory can be arbitrarily set by the system developer. Here, the basic judgment temperature stored in the memory will be described using 77 deg.

The cooling water temperature determination temperature correction constant for the influence of the running wind is set in the memory map according to the average vehicle speed compared to the intake air amount as shown in FIG. 3. 3, for example, when the intake air amount is 10 g / sec, assuming that the average vehicle speed is 50 km / h, the correction constant is 0.9.

Therefore, the cooling water temperature determination temperature correction value is 77 ° C x 0.9, and becomes 69.3 ° C.

As the coolant temperature determination temperature correction value is calculated in the above, the control device 200 compares the calculated coolant temperature determination temperature correction value (for example, 69.3 ° C) with the actual coolant temperature based on the coolant temperature based determination temperature due to the running wind. (S230).

At this time, if the actual cooling water temperature is lower than the basic determination temperature of the cooling water temperature due to the running wind, the control device 200 determines that the cooling water temperature is continuously circulated due to the failure of the thermostat, and thus the thermostat failure stored in the memory. The code is generated and stored in the memory, and at the same time, a warning lamp lighting signal for requesting the driver to check the vehicle engine is output to the driving device 300 (S240).

As an example, if the actual coolant temperature is 68 ° C, since the coolant temperature basic determination temperature due to the running wind is 69.3 ° C, the control device 200 is a thermostat because the actual coolant temperature is lower than the coolant temperature basic determination temperature due to the running wind. It is determined that a failure has occurred in the stat.

The driving device 300 turns on a warning lamp (not shown) provided in the cluster in front of the driver's seat so that the driver can check the signal according to the warning lamp lighting signal output from the control device 200.

However, if it is determined that the actual cooling water temperature is higher than the basic determination temperature of the cooling water temperature due to the running wind, the control apparatus 200 determines that the thermostat is normal and returns to the main routine (S250).

As a result, by applying the change in the cooling water temperature of the vehicle to the factor of lowering the temperature rise due to the running wind, and comparing it with the actual cooling water temperature, it is possible to accurately determine whether or not the thermostat is broken down, and the determination condition can be expanded. By reducing the error judgment, the cost of troubleshooting and the cost can be reduced, and the judgment temperature does not need to be set even when the North American OBD diagnostic constraint is expanded in the future. Can be said to improve diagnostic performance.

As described above, the thermostat fault diagnosis method according to the present invention can accurately determine whether or not the thermostat fails in the vehicle cooling apparatus, and can expand the determination condition, thereby improving the fault diagnosis performance. In addition, it is possible to reduce the cost of troubleshooting and reduce costs by reducing the number of faults, and it is not necessary to set the judgment temperature separately even when the North American OBD diagnosis constraints are expanded in the future. It can be said that performance is improved.

1 is a block diagram of a thermostat failure diagnosis apparatus according to the present invention,

2, a and b is a flowchart illustrating a method for diagnosing a thermostat fault according to the present invention;

3 is a correction constant setting memory map according to the average vehicle speed to the intake air amount according to the present invention.

<Description of Symbols for Main Parts of Drawings>

100: vehicle operation state detection device 110: engine speed detection unit

120: intake air amount detection unit 130: cooling water temperature detection unit

140: vehicle speed detection unit 200: control device

300: warning device

Claims (6)

When the engine is started, accumulating the traveling vehicle speed and determining whether the thermostat failure diagnosis execution condition is satisfied; Setting a determination initial setting time according to the intake air amount when the thermostat failure diagnosis execution condition is satisfied in the above step, and subtracting the initial setting time to 0 time; Determining a change in the intake air amount during the initial setting time reduction in the determination step, resetting the thermostat failure determination time when the intake air amount changes, and subtracting it to zero time; Storing the cooling water temperature and calculating an average of the accumulated vehicle speed when the thermostat failure determination time subtracted in the step reaches 0 time point; Calculating a coolant temperature basic determination temperature correction value according to the driving wind effect according to the average value of the vehicle speed calculated in the step; Thermostat failure diagnosis method comprising the step of determining whether or not the thermostat failure compared to the cooling water temperature basic determination temperature correction value according to the influence of the running wind calculated in the step. 2. The thermostatic fault diagnosis execution condition according to claim 1, wherein the temperature at which the thermostat fault diagnosis is executed is greater than or equal to the first set temperature, less than or equal to the second set temperature, and an absolute difference between the coolant temperature and the intake temperature at start is a third set temperature. And a condition in which the intake air amount is within a fourth set condition of the lowest intake air amount and a fifth set condition of the highest intake air amount. The method of claim 1, wherein the method of subtracting the initial set time up to zero includes subtracting 1 sec every ninth set time. The method of claim 1, wherein the method for resetting the Mostet failure determination time comprises: comparing an average amount of intake air amount sucked into the engine and an amount of intake air at the time of initial setting of the thermostat diagnosis; Determining an area of the average air amount when it is determined that a difference occurs between the average air amount of the intake air amount sucked into the engine and the intake air amount at the time of setting the thermostat initial diagnosis time; Setting the time set in the memory map according to the cooling water temperature at the present time to the subtracted time T1 with respect to the average amount of air determined in the step; Resetting a large value to a time for thermostat failure diagnosis by comparing the subtraction time T1 set at the step and the reduced remaining time T for thermostat diagnosis at a time point at which the intake air amount is varied; And subtracting the reset time by 1 sec for every ninth set time until the time becomes zero. The thermostat failure diagnosis method according to claim 1, wherein the cooling water temperature basic determination temperature correction according to the influence during driving includes calculating and calculating the determination temperature correction constant for the basic determination temperature x driving wind influence stored in the memory. 6. The method of claim 5, wherein the determination temperature correction constant for the influence of the running wind is set in the memory map according to the average vehicle speed relative to the intake air amount.